Optical module

ABSTRACT

An optical module that is easy to manufacture and may arrange and position an optical element mounting substrate and a package with high precision is provided. A substrate side positioning groove portion is formed in an optical element mounting surface of the optical element mounting substrate on which an optical element is mounted, and a package side positioning groove portion is formed in the package on which the optical element mounting substrate is arranged. The optical element mounting substrate and the package are overlapped with each other with the substrate side positioning groove portion and the package side positioning groove portion facing each other. An optical fiber that is a positioning member is inserted between the positioning groove portions. Thus, the optical element mounting substrate and the package are positioned to each other. The respective positioning groove portions on the substrate side and on the package side may readily be formed with high precision. Also, the optical fiber may be manufactured with high precision. Thus, it is possible to position the optical element mounting substrate and the package with very high precision.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an optical module used inoptical communications or data communications.

[0003] 2. Description of the Related Art

[0004] An optical module in which an optical element mounting substratefor mounting optical elements are arranged in a package has been used inoptical communications or the like. Recently, in order to meet arequirement to save cost for the optical module, an optical module whosepackage is made of resin has heretofore been developed.

[0005]FIG. 7A is an exploded view of an optical module proposed inJapanese Patent Application No. Hei 9-007021 as an example of this typeoptical module. FIG. 7B is a perspective view of an example of an outerappearance of the optical module.

[0006] In the optical module 100 shown in FIGS. 7A and 7B, an array typeoptical element 1 in which, for example, light emitting portions orlight receiving portions are arranged in an array is mounted on andfixed to an optical element mounting substrate 2. A pattern of electricsignal wirings 10 is formed on a mounting surface (substrate surface) 28of this optical element 1. Also, V-shaped grooves 9 (having a V-shape incross section) as at least one pair of groove portions for positioningon the substrate side are formed on both sides with respect to theelectric signal wirings 10.

[0007] There are various kinds of the optical elements 1. For example,there is a module in which a semiconductor laser chip having fourchannels for emitting an optical signal is arranged on a substrate, amodule in which a photodiode chip for receiving an optical signal isarranged instead of the semiconductor laser chip, a module in which thesemiconductor laser chip is arranged in the same manner and a photodiodechip for monitoring a light emission condition of the semiconductorlaser chip is provided behind the semiconductor laser chip and the like.Among these optical elements, for example, the optical element thatmeets the specification is selected and mounted on and fixed to theoptical element mounting substrate 2.

[0008] A package 4 is made of resin to have a base portion 31 and a sidewall 32 having a substantially L-shape (an L-shape in cross section)that is in an upright position at an end face of the base portion 31. Atleast one (four in case of FIG. 7A) input/output optical fiber insertionhole 6 is formed in the side wall 32 of this package 4.

[0009] Input/output optical fibers 7 are inserted into the input/outputoptical fiber insertion holes 6, respectively. Each of the input/outputoptical fibers 7 is a short optical fiber for at least one of theoptical input to the optical element 1 and the optical output of a beamoutputted from the optical element 1 to the outside.

[0010] Further, a positioning projection 18 is formed in a positioncorresponding to each of the V-shaped grooves 9 of the optical elementmounting substrate 2 in the package 4. As indicated by the arrow B inFIG. 7A, the substrate surface 28 of the optical element mountingsubstrate 2 is caused to face the surface on which the projections 18are formed in the package 4, with the substrate surface 28 of theoptical element mounting substrate 2 being directed downwardly (in FIG.7A), the optical element mounting substrate 2 is caused to overlap onthe base portion 31 of the package 4, and the projections 18 areinserted and fitted into the V-shaped grooves 9.

[0011]FIG. 8 is a cross-sectional view showing an fitted condition ofthe projections 18 into the V-shaped grooves 9. As shown in FIG. 8, thecross section of the projections 18 is formed into an arcuate shape attheir ends, and the ends contact the groove surfaces of the V-shapedgrooves 9. Then, thus, the projections 18 are inserted and fitted intothe V-shaped grooves 9 so that the package 4 and the optical elementmounting substrate 2 are positioned with each other and the array typeoptical element 1 and the input/output optical fibers 7 are centered andoptically coupled to each other.

[0012] Under the condition in which the optical element mountingsubstrate 2 and the package 4 are overlapped with each other asdescribed above, the region (indicated by reference character A in FIG.7A) between an inner wall surface 32 a of the side wall 32 of thepackage 4 and the optical element 1 is sealed with resin. Thus, theinput/output optical fibers 7 are bonded and fixed to the package 4, atthe same time, the optical element 1 of the optical element mountingsubstrate 2 as a whole is covered by the resin to be sealed.Furthermore, the optical element mounting substrate 2 is fixed to thepackage 4.

[0013] The package 4 in which the optical element mounting substrate 2is provided is mounted on a lead frame package 11 with the opticalelement mounting substrate 2 being directed downwardly as indicated bythe arrow C in FIG. 7A, and fixed by adhesives 30.

[0014] The optical module 100 shown in FIGS. 7A and 7B is constructed asdescribed above. This optical module 100 is constructed so as to beelectrically connectable to a circuit of a mounting substrate (notshown) through a plurality of lead terminals 17 formed in the lead framepackage 11.

[0015] Incidentally, reference numeral 20 in FIGS. 7A and 7B indicatesan opening portion, which is a hole for wire bonding (lines made of goldare arranged from the optical element mounting substrate 2 to the leadframe package 11) and injecting the adhesives 30.

[0016] As described above, with the optical module 100, only theprojections 18 of the package 4 are inserted and fitted in the V-shapedgrooves 9 of the optical element mounting substrate 2 so that the arraytype optical element 1 and the input/output optical fibers 7 arecentered and optically coupled to each other. Thus, it is possible toprovide the optical module that may optically and directly coupling thearray type optical element 1 and the input/output optical fibers 7 witheach other without any lens without using an expensive device.

[0017] However, although the resin made package 4 is molded by transfermolding, injection molding of the resin or the like, there is a problemin that it is technically difficult to form the projections 18 into adesired shape, for example, an arcuate shape having a diameter of about125 μm.

[0018] Namely, in order to form the package 4, as shown in FIG. 9, theresin forming the package 4 is caused to flow into a mold 33 having agroove 33 a for forming the projection 18 and cured. At this time, inorder to form the projection 18 to have an exact size and an exactshape, it is necessary to transfer the groove 33 a of the mold 33exactly with the precision of ±1 μm. In order to attain this, a highprocessing technique is required. Also, in view of the fact that it isdifficult to exactly evaluate the dimension of the machined mold, it isdifficult to enhance the dimensional precision of the mold 33 by feedingback the information of the dimensional error of the molded product.

[0019] For this reason, it is technically difficult to form theprojection 18 with a high precision and exactly in accordance with thedesign as described above. Due to this, it is difficult to preciselyposition the package 4 and the optical element mounting substrate 2 witheach other. Accordingly, it is difficult to perform the precisepositioning of the relative positional relationship between the opticalelement 1 and the input/output optical fiber 7 and to stably realize thehigh optical connection.

SUMMARY OF THE INVENTION

[0020] The present invention has been made in view of the above, and anobject of the present invention is therefore to provide an opticalmodule in which an optical element mounting substrate and a package maybe arranged exactly with each other.

[0021] In order to attain this and other objects, according to a firstaspect of the invention, there is provided an optical module having anoptical element mounting substrate on which an optical element ismounted, and a package made of resin, on which the optical elementmounting substrate is arranged, characterized in that a substrate sidepositioning groove portion is formed in a substrate surface of theoptical element mounting substrate, a package side positioning grooveportion is formed in the package, the package side positioning grooveportion facing the substrate side positioning groove portion byarranging the optical element mounting substrate to face the package,and a positioning member is inserted between the package sidepositioning groove portion and the substrate positioning groove portionwhich face each other.

[0022] According to a second aspect of the present invention, there isprovided an optical module provided with the structure according to thefirst aspect of the invention, and characterized in that at least one ofthe substrate side positioning groove portion and the package sidepositioning groove portion is a groove having a substantially V-shapedgroove in cross section.

[0023] According to a third aspect of the invention, there is providedan optical module provided with the structure according to the firstaspect of the invention, and characterized in that at least one of thesubstrate side positioning groove portion and the package sidepositioning groove portion is a groove having an arcuate groove in crosssection.

[0024] According to a fourth aspect of the invention, there is providedan optical module provided with the structure according to the firstaspect of the invention according to the first aspect of the invention,and characterized in that at least one of the substrate side positioninggroove portion and the package side positioning groove portion has sucha shape that the groove portion may engage with the positioning memberwith almost no gap.

[0025] According to a fifth aspect of the invention, there is providedan optical module provided with the structure according to any one ofthe first to fourth aspects of the invention, and characterized in thatthe positioning member is a columnar member.

[0026] According to a sixth aspect of the invention, there is providedan optical module provided with the structure according to any one ofthe first to fifth aspects of the invention, and characterized in that alinear expansion coefficient of the positioning member is 1×10⁻⁶/K orless.

[0027] According to a seventh aspect of the invention, there is providedan optical module provided with the structure according to any one ofthe first to sixth aspects of the invention, and characterized in thatthe positioning member is an optical fiber.

[0028] According to an eighth aspect of the invention, there is providedan optical module provided with the structure according to any one ofthe first to seventh aspects of the invention, and characterized in thatthe substrate side positioning groove portions are formed on both sidesof the optical element.

[0029] According to a ninth aspect of the invention, there is providedan optical module provided with the structure according to any one ofthe first to eighth aspects of the invention, and characterized in thata length of a part of the positioning member clamped between the opticalelement mounting substrate and the package is one third or more of thesubstrate side positioning groove portion.

[0030] According to a tenth aspect of the invention, there is providedan optical module provided with the structure according to any one ofthe first to ninth aspects of the invention, and characterized in thatthe package has a base portion in which the package side positioninggroove is formed, and a side wall which is formed in an uprightcondition at an end face of the base portion, and a hole for insertionof the positioning member is formed so as to be continuous with thepackage side positioning groove portion.

[0031] According to an eleventh aspect of the invention, there isprovided an optical module provided with the structure according to anyone of the first to tenth aspects of the invention, and characterized inthat an optical fiber to be optically coupled to the optical element ismounted on the package, and the optical fiber and the positioning memberare arranged such that they are substantially in parallel with eachother along their longitudinal direction and the centers thereof aresubstantially in the same flat plane.

[0032] According to a twelfth aspect of the invention, there is providedan optical module provided with the structure according to any one ofthe first to eleventh aspects of the invention, and characterized inthat the optical module further comprises an optical fiber to beoptically coupled to the optical element, wherein the optical fiber isoptically coupled directly to the optical element.

[0033] According to the present invention, a substrate side positioninggroove portion is provided in a substrate surface of the optical elementmounting substrate, a package side position groove portion is formed inthe package, the optical element mounting substrate and the package arearranged with the substrate side positioning groove portion and thepackage side positioning groove portion facing each other, and apositioning member is inserted between the package side positioninggroove portion and substrate positioning groove portion which face eachother. The package positioning portion is in the form of a groove asdescribed above. Thus, it is possible to readily form the mold formolding the package with high precision. Accordingly, it is possible toreadily form the package provided with the exact positioning grooveportion, as a result of which it is possible to provide the opticalmodule that may exactly provide the optical element mounting substrateand the package in place.

[0034] In the case where at least one of the substrate side positioninggroove portion and the package side positioning groove portion issubstantially in the form of a V-shape or in the case where at least oneof the substrate side positioning groove portion and the package sidepositioning groove portion is in the arcuate form, the substantiallyV-shaped groove or the arcuate groove may readily be formed with highprecision. It is therefore possible to enhance the positioning precisionof the optical element mounting substrate and the package.

[0035] In particular, in the case where at least one of the substrateside positioning groove portion and the package side positioning grooveportion has a form to fit the positioning member with almost no gap, thegrooves are intimately fitted with the positioning member so that thepositional displacement of the positioning member to the positioninggroove portions may be avoided. It is thus possible to considerablyenhance the positioning precision of the optical element mountingsubstrate and the package.

[0036] In the case where the positioning member is the columnar member,for example, in the case where at least one of the substrate sidepositioning groove portion and the package side positioning grooveportion is substantially in the form of a V-shape, the columnarpositioning member may be arranged in the substantially V-shaped groovewithout any displacement.

[0037] In the case where the linear expansion coefficient of thepositioning member is at 1×10⁻⁶/K or less, the thermal expansion or thethermal shrinkage of the positioning member due to the temperaturechange is very small whereby it is possible to substantially suppressthe positional displacement of the package and the optical elementmounting substrate caused by the temperature change.

[0038] In the case where the positioning member is the optical fiber, itis possible to form the optical fiber with very high precision, and theoptical fiber is in the form of a columnar shape with its linearexpansion coefficient of 1×10⁻⁶/K or less. Thus, the optical fiber asthe positioning member is inserted and fitted between the substrate sidepositioning groove portion and the package side positioning grooveportion, and the package may be positioned to the optical elementmounting substrate as designed. In addition, it is possible to suppressthe positional displacement of the optical element mounting substrateand the package caused by the temperature change.

[0039] In the case where the substrate side positioning portions areformed on both sides of the optical element, it is possible to arrangethe optical element to the package in the position as designed. It isthus possible to considerably enhance the optical coupling rate of, forexample, the optical element and the optical fiber that is the object tobe optically coupled to and mounted on the package.

[0040] In the case where the length of the part of the positioningmember clamped between the optical element mounting substrate and thepackage is one third or more of the full length of the substrate sidepositioning groove portion, there is no fear that the positioning memberis too short and tilted to the package. It is thus possible to align thepackage and the optical element mounting substrate to each other withoutfail.

[0041] In the case where the hole through which the positioning memberpasses and which is continuous with the package side positioning grooveportion, the positioning member is inserted and arranged into thepackage side positioning groove portion through the hole of the sidewall of the package, so that the positioning member may be positioned ina set position with ease.

[0042] In the case where an optical fiber to be optically coupled to theoptical element is fixed to the package, and the optical fiber and thepositioning member are arranged such that they are substantially inparallel with each other along their longitudinal direction and thecenters thereof are substantially in the same flat plane, it is possibleto position the optical element and the fiber to each other with theoptimum positioning precision and to perform the very good opticalcoupling of the optical element and the fiber.

[0043] As described above, according to the present invention, it ispossible to position the optical element and the optical fiber to eachother with very high precision. It is thus possible to optically couplethe optical element and the optical fiber directly to each other withoutany lens and without using an expensive device to thereby reduce thesize of the optical module.

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] These and other objects and advantages of the present inventionwill become more apparent and more readily appreciated from thefollowing detailed description of the exemplary embodiments of theinvention taken in conjunction with the accompanying drawings, in which:

[0045]FIG. 1A is an exploded view of a primary part of an optical moduleaccording to an embodiment of the present invention;

[0046]FIG. 1B is a perspective view of an example of an outer appearanceof the optical module shown in FIG. 1A;

[0047]FIG. 1C is a side elevational view of an example of a state inwhich another optical component is connected to the optical module shownin FIG. 1A;

[0048]FIG. 2A is a cross-sectional view taken along an extension line ofa straight line D shown in FIG. 1A, showing a state in which an opticalelement mounting substrate is arranged on and fixed to a package of theoptical module;

[0049]FIG. 2B is a cross-sectional view taken along the line A-A′ ofFIG. 2A;

[0050]FIG. 2C is a cross-sectional view taken along the line B-B′ ofFIG. 2A;

[0051]FIG. 3 is a cross-sectional view showing an example of positioningstructure of the package and the optical element mounting substrateshown in FIG. 1A;

[0052]FIG. 4 is a view illustrating an example of a molding process ofan arcuate groove of the package constituting the optical moduleaccording to the present invention;

[0053]FIG. 5A is a perspective view of a package used in anotherembodiment of an optical module according to the present invention;

[0054]FIG. 5B is a cross-sectional view showing an example of apositioning structure of the package and an optical element mountingsubstrate in the optical module in the embodiment;

[0055]FIG. 6 is a view illustrating an example of a molding process ofan inverted W-shaped groove of the package shown in FIG. 5A;

[0056]FIG. 7A is an exploded view of a primary part showing an exampleof a conventional optical module;

[0057]FIG. 7B is a perspective view showing an example of an outerappearance of the optical module shown in FIG. 7A;

[0058]FIG. 8 is a view illustrating an example of a positioningstructure of a package and an optical element mounting substrate in theconventional optical module; and

[0059]FIG. 9 is a view illustrating an example of a molding process ofprojections of the conventional package.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0060] An embodiment of the present invention will now be described indetail with reference to the accompanying drawings. Incidentally, thesame reference numerals are used to indicate the same members and likecomponents as those shown in FIGS. 7A, 7B, 8 and 9. Therefore, theexplanation therefor will be omitted.

[0061]FIG. 1A is an exploded view of an optical module according to anembodiment of the present invention. FIG. 1B is a perspective view of anexample of an outer appearance of the optical module 200 shown in FIG.1A. FIG. 1C is a side elevational view of an example of a state in whichanother optical component 400 is connected to the optical module 200shown in FIG. 1A. Further, FIG. 2A is a cross-sectional view taken alongan extension line of a straight line D shown in FIG. 1A, showing a statein which an optical element mounting substrate 2 is arranged on andfixed to a package 4 of the optical module 200. FIG. 2B is across-sectional view taken along the line A-A′ of FIG. 2A and FIG. 2C isa cross-sectional view taken along the line B-B′ of FIG. 2A, showingthis state, respectively.

[0062] The optical module 200 shown in these drawings according to theembodiment is composed of the optical element mounting substrate 2, thepackage 4 and a lead frame package 11. The structure of each of theoptical element mounting substrate 2 and the lead frame package 11 isthe same as that of the conventional case. This embodiment is differentfrom the conventional case in that, as shown in FIGS. 1A and 2C,positioning grooves are provided in the optical element mountingsubstrate 2 and the package 4, respectively, and positioning members 3for positional alignment are provided between positioning grooveportions 5 of the package 4 and positioning groove portions 9 of theoptical element mounting substrate 2.

[0063] Namely, in this embodiment, each of the grooves 5 having anarcuate cross-section as shown in FIG. 3 (arcuate groove) is formed asthe package side positioning groove portion at a position correspondingto a V-shaped groove 9 of the optical element mounting substrate 2 inthe package 4. As indicated by the arrow B in FIG. 1A, amounting surface(substrate surface) 28 of the optical element 1 is caused to face thesurface of the package 4 where the arcuate groove 5 is formed with thesubstrate surface 28 being directed downwardly in FIG. 1A, and theoptical element 1 is overlapped on the package 4. As shown in FIG. 2C,the V-shaped groove 9 of the optical element mounting substrate 2 andthe arcuate groove 5 of the package 4 are arranged to face each other.The positioning optical fiber 3 (optical fiber) that is the commonpositioning member is inserted between the V-shaped groove 9 and arcuategroove 5 which face each other.

[0064]FIG. 3 shows, in cross section, an engagement state of theV-shaped groove 9 and arcuate groove 5 with the positioning opticalfiber 3. As shown in FIG. 3, in this embodiment, the arcuate groove 5 isformed to have substantially the same diameter as the outer diameter ofthe positioning optical fiber 3. For this reason, the positioningoptical fiber 3 is contacted at two positions with the groove surface ofthe V-shaped groove 9 and engaged with the arcuate groove 5 with almostno gap. The package 4 and the optical element mounting substrate 2 arealigned with each other by the positioning optical fiber 3 and thearcuate groove 5 and V-shaped groove 9. Thus, the array type opticalelement 1 and the input/output optical fibers 7 are optically coupledwith each other in a centered condition.

[0065] For instance, a single mode fiber or the like that is generallyused is used as the positioning optical fiber 3. This single mode fiberis very thin to have a diameter of, for example, about 125 μm. For thisreason, this single mode fiber is used as the positioning optical fiber3 to thereby make it possible to miniaturize the optical module 200. Inaddition, since the single mode fiber has a high molding precisionalthough it is thin as described above, it is possible to considerablyenhance the positioning precision. Furthermore, since the single modefiber is generally made of quartz, the linear expansion coefficient isvery small at 4×10⁻⁷/K or less. It is thus possible to prevent thepositional displacement of the package 4 and the optical elementmounting substrate 2 due to the temperature change. Moreover, since thepositioning optical fiber 3 is formed into a columnar shape, it is easyto perform the positioning by the V-shaped grooves 9.

[0066] The arcuate groove 5 may be formed as follows because thepositioning optical fiber 3 has such a shape that it may engage with thegroove with almost no gap as described above. For instance, as shown inFIG. 4, a V-shaped groove 19 is formed in a mold 13 for molding thepackage 4, and a core pin 14 is arranged in this V-shaped groove 19.Then, upon the molding of the package 4, under this condition, resin iscaused to flow into the mold 13 and cured. Thus, it is possible to formthe arcuate groove 5 along the surface shape of the core pin 14. Sinceboth the V-shaped groove 19 of the mold 13 and the core pin 14 have avery high dimensional precision, it is possible to mold the arcuategroove 5 with very high precision as well.

[0067] In this embodiment, as described above, the arcuate groove 5 maybe molded with very high dimensional precision, and as shown in FIG. 3,the positioning optical fiber 3 may be engaged with the arcuate groove 5with almost no gap. Thus, it is possible to position the positioningoptical fiber 3 with high precision. Further, although adhesives 30 areintroduced in the gap between the optical element mounting substrate 2and the package 4, the positioning optical fiber 3 is substantially incontact with the arcuate groove 5 as described above to thereby make itpossible to reduce the amount of the adhesives 30 to be introducedbetween the two components. Thus, it is possible to prevent thepositional displacement of the positioning optical fiber 3 based uponthe thermal expansion and the thermal shrinkage of the adhesives due tothe environmental temperature change, i.e., the positional displacementbetween the optical element land the input/output optical fibers 7. Inaddition, since the positioning groove portion of the optical elementmounting substrate 2 is formed into the V-shaped groove 9 so that theadhesives are introduced into the gap between the bottom of the V-shapedgroove 9 and the positioning optical fiber 3, the adhesion strength ofthe positioning optical fiber 3 to the optical element mountingsubstrate 2 is sufficient. Furthermore, in this embodiment, a plurality(two in this case) of combinations between the V-shaped grooves 9 andthe arcuate grooves 5 are provided on both sides of the optical element1. It is therefore possible to prevent the positional displacementbetween the optical element 1 and the input/output optical fibers 7 dueto the thermal expansion and the thermal shrinkage of the respectivecomponents caused by the environmental temperature change.

[0068] As shown in FIG. 2B, positioning optical fiber insertion holes 8through which the positioning optical fibers 3 pass are formed on bothsides of the arrangement of input/output optical fiber insertion holes 6in the side wall 32 of the package 4. The formation direction of thesepositioning optical fiber element insertion holes 8 is substantially inparallel with the formation direction of the input/output optical fiberinsertion holes 6. In addition, the centers of these positioning opticalfiber insertion holes 8 are arranged substantially in the same levelwith the centers of the input/output optical fiber insertion holes 6.Moreover, the positioning optical fiber insertion holes 8 are formed tobe continuous with the arcuate grooves 5.

[0069] Since the positioning optical fiber insertion holes 8 are thusformed, the longitudinal directions of the positioning optical fibers 3to be inserted into the positioning optical fiber insertion holes 8 andthe input/output optical fibers 7 to be inserted into the input/outputoptical fiber insertion holes 6 (i.e., the optical fibers to beoptically coupled with the optical element 1) are substantially inparallel with each other, and the centers thereof are substantially inthe same level. In other words, the arrangement is attained such thatthe positioning precision of the input/output optical fibers 7 is atoptimum by the positioning optical fibers 3.

[0070] It is also preferable that a length of the part of thepositioning optical fibers 3 clamped by the optical element mountingsubstrate 2 and the package 4 be one third or more of the full length ofthe V-shaped grooves 9 of the optical element mounting substrate 2. Inview of this, in this embodiment, the positioning optical fibers 3 aresomewhat longer than the full length of the arcuate grooves 5 of thepackage 4.

[0071] Further, in this embodiment, pin fitting recess portions 12opened on the insertion side 25 of the input/output optical fiber asshown in FIG. 1C are formed in positions outside the positioning opticalfiber insertion holes 8. Positioning pins 402 are inserted in the pinfitting recess portions 12 as shown in FIG. 1C. When the optical module200 is connected to another optical component such as an MT (MechanicalTransferable) connector 400 provided with an optical fiber 401 forinput/output of a beam with respect to the input/output optical fibers 7of the optical module 200, the positioning operation with the otheroptical component may readily be performed by these pin fitting recessportions 12 and the positioning pins 402.

[0072] The optical module 200 according to this embodiment isconstructed as described above. An example of the manufacturing processof this optical module 200 will briefly be described. First of all, asshown in FIGS. 1A, the pattern of electric signal wirings 10 is formedon the substrate surface 28 of the optical element mounting substrate 2,and at the same time, the V-shaped grooves 9 are formed on both sides ofthe pattern of the electric signal wirings 10. The optical element 1 isloaded on the substrate surface 28 of the optical element mountingsubstrate 2.

[0073] On the other hand, the package 4 is molded of resin. The arcuategrooves 5, the input/output optical fiber insertion holes 6, thepositioning optical fiber insertion holes 8, the pin fitting recessportions 12 and the opening portion 20 are formed in this package 4.Then, the input/output optical fibers 7 are inserted into theabove-described input/output optical fiber insertion holes 6 and bondedand fixed thereto.

[0074] Subsequently, the substrate surface 28 of the thus manufacturedoptical element mounting substrate 2 is caused to face the arcuategroove 5 formation surface of the package 4, and the optical elementmounting substrate 2 is overlapped on the package 4 with the V-shapedgrooves 9 being aligned with the arcuate grooves 5. At this time, thepositioning optical fibers 3 are inserted through the positioningoptical fiber insertion holes 8 between the V-shaped grooves 9 and thearcuate grooves 5. Thus, the optical element mounting substrate 2 andthe package 4 are positioned in place. Therefore, the array type opticalelement 1 and the input/output optical fibers 7 are centered andoptically coupled directly with each other without using any lens.

[0075] As described above, in this embodiment, the positioning opticalfiber insertion holes 8 are thus provided. For this reason, thepositioning optical fibers 3 are arranged on the arcuate groove portions5 through the positioning optical fiber insertion holes 8 as describedabove so that the arrangement of the positioning optical fibers 3 to thearcuate grooves 5 may readily be performed.

[0076] Subsequently, under the condition that the optical elementmounting substrate 2 is overlapped on the package 4 as described above,the region (indicated by A in FIG. 1A) between the input/output opticalfibers 7 fixture portion of the side wall 32 of the package 4 and theoptical element 1 is sealed with resin. Thus, the fixture of theinput/output optical fibers 7 to the package 4 is performed and at thesame time, the optical element 1 of the optical element mountingsubstrate 2 as a whole is covered with the resin to be sealed.Furthermore, the fixture of the optical element mounting substrate 2 tothe package 4 is performed.

[0077] Thereafter, the package 4 is loaded on the lead frame package 11that has been produced separately with the optical element mountingsubstrate 2 side being directed downwardly as indicated in the arrow Cin FIG. 1A. The wire bonding is effected to the respective lead patternson the optical element mounting substrate 2 and the lead frame package11.

[0078] Thereafter, the adhesives 30 are caused to flow from the openingportion 20 of the package 4 and to be cured. Thus, the package 4 and thelead frame package 11 are fixed to each other to complete the opticalmodule 200.

[0079] As shown in FIG. 1C, such an optical module 200 is mounted on amounting substrate 300 and may be electrically connected to the circuitof the mounting substrate 300 through a plurality of lead terminals 17formed on the lead frame package 11.

[0080] According to this embodiment, as described above, the arcuategrooves 5 for positioning are formed in the package 4. In order to formthe arcuate grooves 5, as described above, the V-shaped grooves 19 areformed in the mold 13 for molding the package, and the resin is causedto flow into the mold 13 under the condition that the core pins 14 areengaged with the V-shaped grooves 19 and is cured. The arcuate grooves 5are thus formed. It is possible to form the V-shaped grooves 19 to themold 13 with very high precision and it is also possible to form thecore pins 14 with high precision, as a result of which the package 4having the arcuate grooves 5 with high dimensional precision may beformed.

[0081] Further, in this embodiment, the arcuate grooves 5 thus formedand the V-shaped grooves 9 on the side of the optical element mountingsubstrate 2 are caused to face each other, and the positioning opticalfibers 3 are fitted between the grooves 5 and 9 which face each other.Thus, the optical element mounting substrate 2 and the package 4 arepositioned to each other. Since the positioning fibers 3 have beenformed with high precision in size and shape conventionally, thepositioning operation of the optical element mounting substrate 2 andthe package 4 by using the positioning optical fibers 3 may readily beperformed with high precision. For this reason, it is possible toperform the optical coupling between the optical element 1 provided onthe optical element mounting substrate 2 and the optical fibers 7 to beinserted into the package 4 with high precision and in a stable manner.

[0082] Incidentally, the present invention is not limited to theabove-described embodiment and may take various forms. For example,although the positioning groove portions on the side of the package arethe arcuate grooves 5 in the foregoing embodiment, the shape of thegrooves is not limited thereto. For example, as shown in FIGS. 5A and5B, the package side positioning groove portions may be formed into aninverted W-shape 12. This inverted W-shaped groove 12 having an invertedW-shape in cross section is formed by the groove defined between twoprojections 35 a and 35 b. In this case, under the condition shown inFIG. 5B, the inverted W-shaped groove 12 and the V-groove 9 on the sideof the optical element mounting substrate 2 are caused to face eachother. The common positioning optical fiber 3 is inserted between theinverted W-shaped groove 12 and V-shaped groove 9 which face each other.Thus, the package 4 and the optical element mounting substrate 2 arepositioned to each other.

[0083] Further, when the package 4 having the inverted W-shaped groove12 is to be formed, as shown in FIG. 6, V-shaped grooves 29 a and 29 bfor forming the inverted W-shaped groove 12 are formed closely in themold 13 for molding the package. It is possible to readily form theV-shaped grooves 29 a and 29 b in the mold 13 with high precision asdescribed above. For this reason, it is possible to form the invertedW-shaped groove 12 in the package 4 with high precision. Thus, even ifthe optical module 200 is constructed by using the package 4 in whichthe package side positioning groove portions are formed into theinverted W-shaped groove 12 as described above, it is possible toprovide the same effect as in the above-described embodiment.

[0084] Further, although the common positioning member to be insertedinto the package side positioning groove portion and the substrate sidepositioning groove portion, which face each other, is used as thepositioning optical fiber 3 in the foregoing embodiment, it is notalways necessary to use the positioning optical fiber 3 as thispositioning member. For instance, it is possible to use a molding pinmade of ceramics or metal having a linear expansion coefficient of, forexample, 1×10⁻⁶/K or less.

[0085] Moreover, in the foregoing embodiment, the V-shaped grooves 9 areformed as the substrate side positioning groove portions in the opticalelement mounting substrate 2. However, the shape of the grooves is notlimited thereto and may be selected as desired.

[0086] Furthermore, although the arcuate grooves 5 are formed as thepackage side positioning groove portions in the package 4 in thisembodiment, and the V-shaped grooves 9 are formed as the substrate sidepositioning groove portions in the optical element mounting substrate 2,each shape, size, number and position of formation of the package sidepositioning groove portions and the substrate side positioning grooveportions are not limited to those of the above-described embodiment andmay be selected suitably to position and fix the positioning members.

What is claimed is:
 1. An optical module having an optical elementmounting substrate on which an optical element is mounted and a package,made of resin and on which said optical element mounting substrate isarranged, further comprising: a substrate side positioning grooveportion formed in a substrate surface of said optical element mountingsubstrate; a package side position groove portion formed in saidpackage, the package side positioning groove portion facing thesubstrate side positioning groove portion by arranging said opticalelement mounting substrate to face said package; and a positioningmember inserted between the package side positioning groove portion andthe substrate side positioning groove portion which face each other. 2.An optical module according to claim 1 , wherein at least one of thesubstrate side positioning groove portion and the package sidepositioning groove portion is a groove having a substantially V-shape incross section.
 3. An optical module according to claim 1 , wherein atleast one of the substrate side positioning groove portion and thepackage side positioning groove portion is a groove having asubstantially arcuate shape in cross section.
 4. An optical moduleaccording to claim 1 , wherein at least one of the substrate sidepositioning groove portion and the package side positioning grooveportion has a shape engages with said positioning member with almost nogap.
 5. An optical module according to claim 1 , wherein saidpositioning member is a columnar member.
 6. An optical module accordingto claim 1 , wherein a linear expansion coefficient of said positioningmember is 1×10⁻⁶/K or less.
 7. An optical module according to claim 2 ,wherein said positioning member is an optical fiber.
 8. An opticalmodule according to claim 3 , wherein said positioning member is anoptical fiber.
 9. An optical module according to claim 4 , wherein saidpositioning member is an optical fiber.
 10. An optical module accordingto claim 7 , wherein the substrate side positioning groove portion isformed on each side of said optical element.
 11. An optical moduleaccording to claim 8 , wherein the substrate side positioning grooveportion is formed on each side of said optical element.
 12. An opticalmodule according to claim 9 , wherein the package side positioninggroove portion is formed on each side of said optical element.
 13. Anoptical module according to claim 11 , wherein a length of a part ofsaid positioning member clamped between said optical element mountingsubstrate and said package is one third or more of the full length ofthe substrate side positioning groove portion.
 14. An optical moduleaccording to claim 13 , wherein said package has a base portion in whichthe package side positioning groove portion is formed, and a side wallwhich is formed in an upright condition at an end face of said baseportion, and wherein a hole for insertion of said positioning member isformed so as to be continuous with the package side positioning grooveportion.
 15. An optical module according to claim 3 , wherein an opticalfiber to be optically coupled to said optical element is mounted on saidpackage, and said optical fiber and said positioning member are arrangedsuch that they are substantially in parallel with each other along theirlongitudinal direction and the centers thereof are substantially in thesame flat plane.
 16. An optical module according to claim 7 , wherein anoptical fiber to be optically coupled to said optical element is mountedon said package, and said optical fiber and said positioning member arearranged such that they are substantially in parallel with each otheralong their longitudinal direction and the centers thereof aresubstantially in the same flat plane.
 17. An optical module according toclaim 14 , wherein an optical fiber to be optically coupled to saidoptical element is mounted on said package, and said optical fiber andsaid positioning member are arranged such that they are substantially inparallel with each other along their longitudinal direction and thecenters thereof are substantially in the same flat plane.
 18. An opticalmodule according to claim 1 , further comprising an optical fiber to beoptically coupled to said optical element, wherein said optical fiber isoptically coupled directly to said optical element.
 19. An opticalmodule according to claim 11 , further comprising an optical fiber to beoptically coupled to said optical element, wherein said optical fiber isoptically coupled directly to said optical element.
 20. An opticalmodule according to claim 17 , further comprising an optical fiber to beoptically coupled to said optical element, wherein said optical fiber isoptically coupled directly to said optical element.